Iron
Measures level of iron to assess iron deficiency or iron overload
What is being tested?
Iron is an essential nutrient that, among other functions, is required for the production of healthy red blood cells (RBCs). It is a critical part of hemoglobin, the protein in RBCs that binds oxygen in the lungs and releases it as blood circulates to other parts of the body. The serum iron test measures the amount of iron in the liquid portion of blood.
Serum iron is almost always measured with other iron tests, such as serum ferritin, transferrin and total iron-binding capacity (TIBC). These tests are often ordered at the same time and the results interpreted together to help diagnose and/or monitor iron deficiency or iron overload.
The body cannot produce iron and must absorb it from the foods we eat or from supplements. Once absorbed, it is transported throughout the body by binding to transferrin, a protein produced by the liver.
In healthy people, most of the iron absorbed is incorporated into the hemoglobin inside RBCs. The remainder is stored in the tissues as ferritin or hemosiderin, with additional small amounts used to produce other proteins such as myoglobin and some enzymes.
When the level of iron is insufficient to meet the body’s needs, the iron level in the blood drops and iron stores are depleted. This may occur because:
- Not enough iron is consumed (either foods or supplements)
- The body is unable to absorb iron from the foods eaten in conditions such as celiac disease
- There is an increased need for iron, such as during pregnancy or childhood, or due to a condition that causes chronic blood loss (e.g., peptic ulcer, colon cancer)
Insufficient levels of circulating and stored iron may eventually lead to iron deficiency anemia (decreased hemoglobin). In the early stage of iron deficiency, no physical effects are usually seen and the amount of iron stored may be significantly depleted before any signs or symptoms of iron deficiency develop. If a person is otherwise healthy and anemia develops over a long period of time, symptoms seldom appear before the hemoglobin in the blood drops below the lower limit of normal.
However, as the iron-deficiency progresses, symptoms eventually begin to develop. The most common symptoms of anemia include fatigue, weakness, dizziness, headaches and pale skin.
On the other hand, too much iron can be toxic to the body. Iron blood levels and iron storage increase when more iron is absorbed than the body needs. Absorbing too much iron can lead to progressive accumulation and damage to organs such as the liver, heart, and pancreas. An example of this is hemochromatosis, a genetic disease in which the body absorbs too much iron, even on a normal diet. Additionally, iron overdose can occur when someone consumes more than the recommended amount of iron.